Portable pump

ABSTRACT

A reciprocating air compressor arrangement includes a crank that drives a connecting rod and a piston within a cylinder. The connecting rod has a first end and a second end. The first end of the connecting rod is connected to the crank and the second end of the connecting rod is connected to the piston, with the crank provided to actuate the piston in a reciprocating motion within and relative to the cylinder so as to compress air within the cylinder. The reciprocating air compressor arrangement has a one-way flapper inlet valve allowing air to enter the cylinder, and a one-way outlet valve allowing compressed air to exit the cylinder. The inlet valve is biased to a partially open position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Australian Patent Application No.2021901420, filed on May 13, 2021, which is incorporated herein byreference in its entirety.

FIELD OF INVENTION

The present invention relates to a reciprocating air compressorarrangement. The invention has particular application in the context ofa portable, hand-held pump for filling objects with gases such as airand so will hereinafter generally be described in this context.

It is to be appreciated, however, that the invention is not limited toportable hand-held pumps. The invention may be applied to a range of aircompressor sizes and designs, including those used in commercial,industrial and domestic applications.

BACKGROUND

Pumps used to fill objects to a high pressure typically incorporate areciprocating air compressor. These types of compressors tend to belarge and heavy in size and require an external power supply. This, inturn, makes such pumps difficult to transport and less useful if anexternal power supply is not readily available.

The above problems are exacerbated for cyclists who require portability,a pump that is light weight, and one that pumps up tires quickly. Whilesome cyclists use carbon dioxide canisters (known as CO2 inflators),these canisters have a number of disadvantages, including the fact thatthey are intended for only a single use. Another problem is that theybecome very cold during use and may expose a user to potential burns,particularly on their hands and fingers.

Other pumping solutions include traditional manual hand pumps, oftendesigned to be releasably mounted to and carried on a bicycle frame.These are light weight but are slow to use, in that they require arelatively large amount of time to inflate a tire.

While some portable, battery powered air pumps do exist, they tend to beof a relatively large size, cumbersome, of substantial weight (500grams, or more), and are designed to be stand-alone. However, due to therecent advances in high discharge lithium batteries, small, highpressure compressors are starting to be realized. The Applicant'scommercially successful FUMPA™ bike pump, the subject of foreignpatents, and recently allowed U.S. patent application Ser. No.15/750,130, describes a portable pump, whereby a reciprocating aircompressor is actuated by a brushless motor via a gear assembly, and ispowered by a high discharge lithium battery. The components are allcontained within a thermally conductive housing thereby improving thethermal efficiency of the compressor.

A potential limitation noted by the Applicant in the pump of allowedU.S. patent application Ser. No. 15/750,130 is that it is impracticalfor a cyclist to carry the unit in their cycling jersey pocket, giventhe relatively large size and the weight of the unit. The relativelylarge size is mainly due to the use of a bulky gear assembly to drivethe compressor via the brushless motor. As the pump is too large todirectly engage onto a bicycle tire's valve, a hose and fittingarrangement is provided to supply compressed air from the unit to thetire. Further to this, the inflation time of the pump described inallowed U.S. patent application Ser. No. 15/750,130 is very sensitive tothe compressor's compression ratio. Very high compression ratios arerequired to reduce the inflation time of a bicycle tire. The highcompression ratios require clearances smaller than 0.2 mm between thecompressor's piston and the top of the compressor's cylinder when thepiston is at top dead center, and such clearances can only be achievedusing expensive CNC machining processes. This adds significant time andcost to manufacturing of the compressor parts, which is undesirable.

The Applicant's commercially successful miniFUMPA™, the subject offoreign patents, including U.S. Pat. No. 10,837,433, is a more portablepump than their FUMPA™ pump and so has, at least in part, addressed theportability issue of the FUMPA™ pump referred to above. The Applicant'sminiFUMPA™ is the smallest electric pump currently available. However,it has a weight of around 200 grams, a pump length of around 75 mm, aheight of around 70 mm (not including the nozzle) and a thickness 30-35mm, making it too big to fit into a pocket, or a small handbag.

Thus, there is a need for a truly pocket-sized pump, having a weight ofaround 100 grams, a height of less than around 50 mm and a thicknessaround 25 mm. At this weight and dimensions, the pump could be taken onany bicycle journey in a user's pocket or in very small carry bag orhandbag. Commuter cyclists would likely find such a pump appealing, asit could be placed in their bag or pocket on their way to work.

It would therefore be desirable to provide an air compressor arrangementof a very small size, and which can be incorporated into abattery-powered pump. Moreover, it would be desirable to provide abattery-powered pump design that is pocket sized, rechargeable, and canachieve fast pump up times that are less sensitive to the compressor'scompression ratio. Finally, it would be desirable to provide a portablebattery-powered bike pump that is dimensionally smaller than currentlyavailable bike pumps.

Finally, it would be desirable to provide an air compressor arrangementthat at least partially addresses the issue of the compressor motorhaving to overcome an initially high start-up torque which can easilyresult in motor and/or circuit burnout; and which may desirably obviatethe need for the given air compressor to require an unloader valve,which is a common air compressor failure point.

Before turning to a summary of the present invention, it is to beappreciated that the discussion of the background to the invention isincluded to explain the context of the invention. This is not to betaken as an addition that any of the material referred to is published,known or part of the common general knowledge.

The contents of the applicant's U.S. patent application Ser. No.15/750,130 and U.S. Pat. No. 10,837,433 are herein incorporated byreference.

SUMMARY OF THE INVENTION

According to a broad aspect of the present invention, there is provideda reciprocating air compressor arrangement. The arrangement includes acrank that drives a connecting rod and a piston within a cylinder. Theconnecting rod has a first end and a second end. The first end of theconnecting rod is connected to the crank and the second end of theconnecting rod is connected to the piston. The crank is provided toactuate the piston in a reciprocating motion within and relative to thecylinder so as to compress air within the cylinder. The reciprocatingair compressor arrangement has a one-way flapper inlet valve allowingair to enter the cylinder, and an outlet valve allowing compressed airto exit the cylinder. The inlet valve is biased to a partially openposition and, during use, is movable between the partially openposition, a closed position and a fully open position.

Reference to a ‘flapper valve’ in this specification is to be consideredinterchangeable with the term ‘reed valve’.

The outlet valve may be of any suitable one-way valve design. Like theinlet valve, the outlet may be a flapper valve. However, other outletvalve types are also contemplated, including a check valve.

Preferably, the cylinder includes a cylinder head, and the outlet valveincludes an outlet port, with the outlet port extending through thecylinder head to allow for a flow of compressed air to exit thecylinder.

In one preferred form of the invention, the inlet valve includes aninlet port, with the inlet port extending through the cylinder head toallow for a flow of air to enter the cylinder.

In another preferred form of the invention, the piston includes a pistonhead, and the inlet valve includes an inlet port, with the inlet portextending through the piston head to allow for a flow of air to enterthe cylinder.

It is envisaged that the air compressor arrangement is preferablyswitchable between ON and OFF modes, and the inlet valve remains in thepartially open position when the air compressor arrangement is in theOFF mode.

The reciprocating air compressor arrangement of the present inventionhas a number of potentially useful applications, especially in thecontext of a portable pump. In this regard, and according to anotherbroad aspect of the present invention, there is provided a portable pumpincluding a reciprocating air compressor arrangement generally of thetype referred to above. The reciprocating air compressor arrangementincludes a crank that drives a connecting rod and a piston within acylinder. The connecting rod has a first end and a second end. The firstend of the connecting rod is connected to the crank and the second endof the connecting rod is connected to the piston. The crank is providedto actuate the piston in a reciprocating motion within and relative tothe cylinder so as to compress air within the cylinder. Thereciprocating air compressor arrangement includes a one-way flapperinlet valve allowing air to enter the cylinder, and an outlet valveallowing compressed air to exit the cylinder. The portable pump furtherincludes an electric motor having a drive shaft mounted to the crank,with the drive shaft rotatable about a drive shaft axis, and with thedrive shaft axis at least substantially coaxially aligned with an axisof rotation of the crank. The portable pump further includes a controlunit in electrical communication with the electric motor to controloperation of the pump; and a power supply in electrical communicationwith the control unit to supply power to the control unit and electricmotor. The electric motor, the reciprocating air compressor arrangement,the control unit and the power supply are each contained within a commonhousing. An outlet is fluidly connected to the outlet valve of thereciprocating air compressor arrangement for fluidly engaging with anobject to be pumped. The inlet valve is biased to a partially openposition and, during use, is movable between the partially openposition, a closed position and a fully open position.

The portable pump is preferably switchable between ON and OFF modes,with the inlet valve remaining in the partially open position when theportable pump is in the OFF mode.

In one preferred embodiment, the power supply of the portable pump is arechargeable battery having a C rating of at least approximately 20, andcapable of providing a maximum current of at least 4 Amps.

The electric motor of the portable pump is preferably a brushless DCmotor having a motor diameter of between approximately 20 and 30 mm and,more preferably, approximately 23 mm.

In a preferred form, the pump has a total weight of less than 100 grams,and can pump up at least one bicycle road or commuter bike tire toapproximately 80 psi on a single charge.

The invention has the potential for incorporating a housing of verysmall dimensions when compared to the housings of existing portablepumps. In this regard, the housing may have a length of betweenapproximately 45 and 65 mm, a height of less than approximately 50 mm,and a width (or thickness) of approximately 25 mm.

In a preferred form, the pump outlet is provided on or mounted to thehousing. The outlet may include a collar extending outwardly from thehousing, with the collar including a valve receiving bore for receivinga valve of the object to be pumped.

BRIEF DESCRIPTION OF THE DRAWINGS

It will be convenient to hereinafter describe preferred embodiments ofthe invention with reference to the accompanying figures. Theparticularity of the figures is to be understood as not limiting thepreceding broad description of the invention.

FIG. 1 is a schematic side view of a prior art air compressorarrangement.

FIG. 2 is a schematic side view of another prior art air compressorarrangement.

FIGS. 3a to 3c show further schematic side views of a prior art aircompressor arrangement similar to that of FIG. 1, with FIGS. 3a to 3cshowing an operating sequence of the air compressor arrangement.

FIGS. 4a to 4c show schematic side views of another prior art aircompressor arrangement, with FIGS. 4a to 4c showing an operatingsequence of the air compressor arrangement.

FIGS. 5a to 5d show schematic side views of an air compressorarrangement according to a first embodiment of the present invention,with FIGS. 5a to 5d showing an operating sequence of the air compressorarrangement.

FIGS. 6a to 6d show schematic side views of an air compressorarrangement according to a second embodiment of the present invention,with FIGS. 6a to 6d showing an operating sequence of the air compressorarrangement.

FIG. 7 is an isometric view of a portable pump according to the presentinvention. FIG. 7 also provides a size comparison of the portable pumpof the present invention with the applicant's existing FUMPA™ andminiFUMPA™ portable pumps, which are the respective subjects of allowedU.S. patent application Ser. No. 15/750,130 and U.S. Pat. No.10,837,433.

DETAILED DESCRIPTION

As referred to previously, there is growing demand for portable, batterypowered bicycle pumps in the cycling industry. Current electric bikepumps are generally large and cumbersome, weighing around 500 grams.These pumps are far too big to mount onto a bicycle or fit in one'spocket. The applicant's miniFUMPA™ pump (the subject of U.S. Pat. No.10,837,433) is the smallest electric pump currently available. However,it has a weight of around 200 grams, a length of approximately 75 mm, aheight of approximately 70 mm (not including the nozzle) and a thickness(or width) of around 30-35 mm. This makes it too big to fit into apocket, or a small handbag. As stated previously, there is a need for atruly pocket-sized pump, having a weight of around 100 grams, a heightof less than 50 mm and thickness of around 25 mm. At this weight anddimension, the pump could be taken on practically any bicycle journey ina user's pocket or very small carry bag/handbag. Commuter cyclists wouldfind such a pump appealing as it could be placed in their bag or pocketon their way to work.

To realize such a small pump, all aspects of the pump need to beminiaturised. Electric bike pumps generally consist of a reciprocatingair compressor, a motor to drive the air compressor, a battery for useas the power source, control circuitry and enclosure to house all parts.The bulk of the size and weight of a pump comes from the air compressor,motor and battery. Therefore, in order to reduce the size and weight,these three components must be made as small as possible.

FIG. 1 shows the basic design of a prior art reciprocating aircompressor 10. The main components are the crank 12, driven by the motor(not shown), which moves the piston 14 up and down within a cylinder 16via a connecting rod 18. A one-way flapper inlet valve 20 (having aninlet port 20 a) brings air into the cylinder 16 when the piston 14 ismoving in a downwards direction, whilst a one-way flapper outlet valve22 (having an outlet port 22 a) allows compressed air to be removed fromthe top 24 of the air compressor 10 when the piston 14 is moving in anupwards direction. The Force (Fc) required to drive the piston 14 up tothe top of the cylinder 16 can be estimated as follows:

$\begin{matrix}{F_{c} = {F_{m}{\cos\left( \theta_{1} \right)}}} & (1)\end{matrix}$ Where $\begin{matrix}{F_{m} = \frac{\tau}{L_{c}}} & (2)\end{matrix}$

Where τ is the torque the motor can provide.

Reducing parameters such as cylinder diameter (and therefore pistondiameter), or crank size (and therefore length L_(c)) will reduce thevolume of air being compressed, which in turn reduces the compressionratio. This will undesirably result in an increase in pump up time andthe maximum pressure the pump can achieve. A certain amount of reductioncan be tolerated depending on how long a user can wait for their tire tobe pumped, or what pressure they need. However, too much reduction inthese dimensions will result in a pump that is less useful. Further tothis, inlet and outlet valves need to be mounted to the air compressor,and these can only be reduced in size within practical limits beforetheir performance is reduced to their detriment.

One parameter that can be reduced is the length of the connecting rod18, as shown in the prior art air compressor of FIG. 2. Reducing thelength of the connecting rod 118 in FIG. 2 (compared to the length ofthe connecting rod 18 in FIG. 1) reduces the overall height of the aircompressor, whereby L₂<L₁. However, in doing so θ₂>θ₁, and so a smallercrank force F_(c) is generated for the same amount of motor torque. Thisreduction in F_(c) is detrimental, especially when the designer isattempting to design an air compressor 10/110 that can be driven by thesmallest motor possible. Miniature motors (both brushed and brushless)are inefficient in nature, and they generally only achieve high torqueswhen run at maximum speeds. Therefore, on start-up, the available motortorque is a design constraint. For small motors, available motor torqueis generally proportional to motor diameter. As motor diameter is one ofthe main parameters affecting the pump thickness dimension, there aredifficulties in trying to provide enough torque to rotate the aircompressor 10/110, whilst using a motor of suitable small diameter.

Larger air compressors overcome this motor torque limitation byobviously selecting a larger sized motor. Further to this, designerswill often design a low-pressure volume directly after the outlet valveso that on motor start-up, the air compressor is pumping air into avolume that is essentially at zero-gauge pressure. This is achievedthrough use of non-return and/or exhaust valves. Due to size constraintshowever, such a design is not achievable on a miniature air compressor.

FIGS. 3a to 3c illustrate an operating sequence of prior art aircompressor 210. Air compressor 210 is very similar to air compressor 10shown in FIG. 1. FIG. 3a shows the air compressor 210 in its at-restposition. It can be seen that in the at-rest position the one-wayflapper inlet valve 220 (having an inlet port 220 a) and the one-wayflapper (or reed) outlet valve 222 (having an outlet port 222 a) areboth biased into their respective closed positions. As shown in FIG. 3b, when the piston 214 moves in a downwards direction Y1 within thecylinder 216 the negative air pressure temporarily created within thecylinder chamber 217 causes the inlet valve 220 to open, therebyallowing the inflow of air into the chamber 217. The inlet valve 220closes once the piston 214 reaches its lowermost position within thecylinder 216. When the piston 214 moves in an upwardly direction Y2 (seeFIG. 3c ) within the cylinder 216, the inlet valve 220 remainstemporarily closed, but the increasing pressure within the chambercauses the outlet valve 222 to open, through which compressed air isexpelled from within the chamber 217.

FIGS. 4a to 4c illustrate an operating sequence of prior art aircompressor 310. The operation of air compressor 310 is similar to thatof air compressor 210 shown in FIGS. 3a to 3c . However, one fundamentaldifference between air compressors 210 and 310 is that the inlet valve220 of air compressor 210 is mounted in the cylinder head 216 a, whereasthe inlet valve 320 of air compressor 310 is mounted within the pistonhead 314 a.

It can be seen in FIG. 4a that in the at-rest position the one-wayflapper inlet valve 320 and the one-way flapper outlet valve 322 arebiased into their respective closed positions. As shown in FIG. 4b ,when the piston 314 moves in a downwards direction Y3 within thecylinder 316 the negative air pressure temporarily created within thecylinder chamber 317 causes the inlet valve 320 to open, therebyallowing the inflow of air into the chamber 317. The inlet valve 320closes once the piston 314 reaches its lowermost position within thecylinder 316. When the piston 314 moves in an upwardly direction Y4 (seeFIG. 4c ) within the cylinder 316, the inlet valve 320 remainstemporarily closed, but the increasing pressure within the chambercauses the outlet valve 322 to open, through which compressed air isexpelled from within the chamber 317.

Reciprocating air compressors 210/310 of the type shown in FIGS. 3a to3c and 4a to 4c generally rely on reed (or flapper) one-way valves tolet air into and out of the cylinder. These valves are usuallymanufactured from high fatigue strength thin steel material. They aregenerally cantilevered, flat in shape and move up and down depending inthe pressure differential they experience on each of their surfaces.

If an air compressor like the one shown in FIGS. 3a to 3c (or that shownin FIGS. 4a to 4c ) is connected to a bicycle tire that is already at ahigh pressure (50 psi for example), then on motor start-up, asignificant motor torque might be required to turn the crank from astationary position and to open the outlet valve 222. Further to this,as reed valves are simple structures that often do not have the luxuryof a high-quality seals, the outlet valve 222 can leak, causing pressureinside the cylinder 216 to be equal to the pressure inside the tire.This results in very high start-up torques being needed to start thecompression process. If the motor cannot provide the torque, the motorstalls and can result in motor and/or circuit burnout.

To overcome this issue, the applicant has found that this increase inmotor torque requirement can be offset by changing the shape of theinlet valve 220 to that shown in FIGS. 5a to 5d (and that shown in FIGS.6a to 6d ).

One embodiment of the invention is now shown in FIGS. 5a to 5d , whereina reciprocating air compressor arrangement 410 of a portable bike pump400 (see FIG. 7) according to one embodiment of the present invention isillustrated.

The arrangement 410 includes a crank (not shown) that drives aconnecting rod 418 and a piston 414 within a cylinder 416. Theconnecting rod 418 has a first end (not shown) and a second end 421. Thefirst end of the connecting rod 418 is connected to the crank and thesecond end 421 of the connecting rod 418 is connected to the piston 414.The crank is provided to actuate the piston 414 in a reciprocatingmotion within and relative to the cylinder 416, so as to compress airwithin the cylinder 416. The arrangement 410 has a one-way flapper inletvalve 420 with an inlet port 420 a allowing air to enter the cylinder416, and a one-way flapper outlet valve 422 (with an outlet port 422 a)allowing compressed air to exit the cylinder 416. It is to beappreciated that, if desired, the outlet valve 422 need not be a flappervalve. For example, the outlet valve could be a check valve. FIG. 5ashows the arrangement at rest, whereby the piston 414 is stationarywithin the cylinder 416. It is important to appreciate from FIG. 5a thatthe inlet valve 420 is biased into a partially open position when thearrangement 410 is at rest. The fact that the inlet valve 420 ispartially open when the arrangement 410 is at rest is considered uniqueto the present bike pump; and is also considered unique to theapplicant's inventive air compressor arrangements.

The inlet valve 420 is, during use, movable between the partially openposition shown in FIGS. 5a and 5c , the closed position shown in FIG. 5d, and the fully open position shown in FIG. 5 b.

The outlet valve 422 is movable between the closed positions shown inFIGS. 5a to 5c , and the open position shown in FIG. 5 d.

FIG. 5a shows the air compressor 410 in its at-rest position, with theone-way flapper inlet valve 420 in a partially open position, and theone-way flapper outlet valve 422 in a closed position. As shown in FIG.5b , when the piston 414 moves in a downwards direction Y5 within thecylinder 416 the negative air pressure temporarily created within thecylinder chamber 417 causes the inlet valve 420 to further open, therebyfurther allowing the inflow of air into the chamber 417. The outletvalve 422 remains in its closed position. The inlet valve 420 returns toits partially open position when the piston commences moving in theupwards direction Y6 shown in FIG. 5c , whereby a small amount of aircan still escape through the inlet port 422 a. However, when the piston414 approaches its uppermost position in the cylinder shown in FIG. 5d ,sufficient air pressure within the cylinder 416 is created to fullyclose the inlet valve 420, and also open outlet valve to allowpressurized air to exit through outlet port 422 a.

From the above comments, it is to be understood that the shape of theinlet valve 420 is designed so that it is encouraged to leak, which iscounter the design of conventional valves. This is achieved bymanufacturing the inlet valve 420 with a curve so that it sits open inits at-rest state. When the motor is stationary (and the piston 414 istherefore stationary) air inside the cylinder 416 is maintained atzero-gauge pressure. Even if the outlet valve 422 is leaking whenengaged onto a bicycle tire, the curve in the inlet valve 420 ensuresair can escape from the cylinder 416 to the atmosphere.

On motor start-up, if the piston 414 is moving in the downwarddirection, the inlet valve 420 will further open to ensure air isentering the cylinder 416. Once the piston 414 moves upwards (as shownin FIG. 5c ) air will initially leak through the inlet valve 420. Thisgreatly reduces the torque requirements on the motor to turn the crank.Once the motor gets to its top running speed (and therefore able toprovide its highest level of torque), the applicant has found that theinlet valve 420 would close fully when the piston 414 was moving in anupward position (shown in FIG. 5d ), desirably resulting in adequate aircompression during the reciprocating process.

The applicant has found that utilizing curved inlet valves allowedbrushless out-runner motors as small as 23 mm in diameter to power 14 mmdiameter air compressor pistons/cylinders. The applicant did find atrade-off, however. A curved inlet valve 420 resulted in a reduction inmaximum achievable pressure. For small volume tires (for example, roadbicycle tires, 700×23 c, approximately 800 ml in volume), a pressure ofonly about 80-90 psi is achievable; while for larger commuter bike tires(700×28 c up to 700×35 c tires) a pressure of about 70-80 psi isachievable. These pressures are less than what is achievable withtraditional flat reed valve designs (120 psi and greater). However, ascommuter bicycle tires only require pressures of up to 80 psi, thismethod to reduce the required motor torque is a plausible solution.

One of the other constraints of a pocket-sized pump is the size of thebattery. Motor driven air compressors require large currents, and sohigh discharge lithium polymer batteries are commonly used to supplypower. However, there is a limit to the amount of current that can bedrawn from a battery. The battery must be able to handle the highcurrents required to drive the compressor, without affecting isperformance, or worse, being damaged due to excessive current draw.

The rate (C) at which a battery can be safely discharged is dependent onboth the maximum discharge current (I) that the battery experiences, andthe battery's capacity (ρ). These three variables are related asfollows:

I=ρC

Battery sizes of similar dimension to miniature motors (23 mm) can bemanufactured with a C rating of approximately 20 C. This is less thanthe current design requirements of the pump the subject of U.S. Pat. No.10,837,433. For high discharge lithium batteries currently available insizes close to the diameter of the motor requirements of a miniaturepump, 200-300 mAh batteries are an option. Therefore, from the equationabove, a maximum current of only 4-6 Amps of current is available fromsuch small batteries.

The applicant has found that if a flat inlet valve (such as of the priorart types illustrated in FIGS. 1 to 4 c) is used, it was almostimpossible to achieve tire pressures greater than 50 psi without motorstall occurring. Further to this, currents exceeding 6 Amps were common.However, using a curved inlet valve resulted in tire pressures exceeding80 psi and currents of less than 5 amps were possible. The provision ofa curved inlet valve ensured pressures were achievable whilst ensuringbatteries were not being damaged due to excessive current draw.

FIGS. 6a to 6d illustrate an operating sequence of an air compressorarrangement 510 according to another embodiment of the presentinvention. The operation of air compressor arrangement 510 is similar tothat of air compressor arrangement 410 shown in FIGS. 5a to 5d . Onefundamental difference between air compressor arrangements 410 and 510is that the inlet valve 420 of air compressor arrangement 410 is mountedin the cylinder head 416 a, whereas the inlet valve 520 of aircompressor arrangement 510 is mounted within the piston head 514 a. Inother respects, air compressor arrangements 410 and 510 are the same.

FIG. 7 shows an embodiment of micro bicycle tire pump 400 according toan embodiment of the present invention in isometric view.

Advantageously, the pump 400 is extremely light weight, with a totalweight of less than 100 grams. The pump 400 is capable of pumping up atleast one bicycle road or commuter bike tire to approximately 80 psi ona single charge.

The pump 400 includes a novel reciprocating air compressor arrangementgenerally of the type previously described.

The pump 400 includes a housing 402. Within the housing 400 (andtherefore not clearly shown) there is provided a power supply in theform of a high discharge lithium battery, and an electric motor having adrive shaft that connects directly to the reciprocating air compressorarrangement. In this regard, the drive shaft is rigidly mounted to thecrank, with the rotation axes of the drive shaft and the crank aligned.

The electric motor is in the form of a brushless DC motor having a motordiameter of between approximately 20 and 30 mm and, more preferably,approximately 23 mm.

Although not shown in FIG. 7, the housing of pump 400 includes a chargeport. The charge port allows the use of an external charger to chargethe pump's internal battery.

The pump 400 includes a compressed air outlet 404 for engagement with abicycle tire valve (not shown). The outlet 404 is fluidly connected tothe outlet valve of the reciprocating air compressor arrangement. Theoutlet 404 is mounted on or to the housing 402, and includes a valvereceiving bore 406 for receiving a valve of the tire (or other object)to be pumped. As the pump 400 is so small, it easily fits between thespokes of a bicycle wheel without use of a hose extending between theoutlet 404 and the tire valve.

The pump 400 further includes a control unit in electrical communicationwith the electric motor to control operation of the pump and the powersupply. The control unit may be a printed circuit board that consists ofcontrol circuitry that turns the motor ON and OFF via a switch andmonitors the battery's voltage.

In operation, the portable pump 400 is turned on by a user via switch408. Once turned on, the electric motor starts running which, in turn,rotates the drive shaft. The rotating drive shaft turns/rotates thecrank, causing the connecting rod and piston to reciprocate axiallywithin the cylinder. One-way flapper inlet and outlet valves of the aircompressor arrangement ensure that air is compressed inside the cylinderand forced through the outlet 404. This process is carried out manytimes a second as the piston axially reciprocates within the cylinder.The unique design of the inlet valve, whereby it is biased into apartially open position (including when the pump is initially turnedON), desirably avoids the need for the motor to overcome an initiallyhigh start-up torque which can easily result in motor and/or circuitburnout.

Advantageously, the design of the portable pump 400 allows it to bemanufactured small enough so that it can be mounted directly onto a tirevalve. Indeed, the pump 400 can be considered to be of a micro size whencompared to existing pump designs, including the applicant's pumps thesubjects of U.S. Pat. No. 10,837,433 and U.S. patent application Ser.No. 15/750,130. This means that no additional hose or fittings arerequired to transfer the compressed air to the tire, as the pump can fitbetween most conventional 700 mm diameter bicycle wheel spokeconfigurations and directly onto the tire valve, thereby furtherreducing the size and weight of the pump 400. The pump 400 ismanufactured without a gearbox or outlet hose, and so this enables thepump 400 to be of a very small size when compared to existing pumpdesigns. The pump 400 has a length only in the order of approximately 45to 65 mm, a height of less than approximately 50 mm and a width (orthickness) of approximately 25 mm. These small dimensions allow the pumpto fit easily into a cyclist's jersey pocket or small handbag.

FIG. 7 is useful in that it provides size comparisons between theapplicant's new pump 400, and their existing (and market leading) pumps500, 600, the subjects of U.S. Pat. No. 10,837,433 and allowed U.S.patent application Ser. No. 15/750,130, respectively. It is important toappreciate that the smaller dimensions of their latest pump 400 comparedto their existing pumps 500, 600 hasn't been achieved simply byminiaturizing components of the pumps 500, 600 such that they fit intothe smaller housing 402 of pump 400. Instead, the smaller size of pump400 was the result of considerable re-design and invention by theapplicant and, in particular, the complete re-design of the inlet valveof the air compressor arrangement.

Finally, it is to be appreciated that the applicant's unique inlet valvedesign could conceivably be applied to any conventional air compressorarrangement. This, in turn, may desirably obviate the need for a givenair compressor arrangement to require an unloader valve, which is acommon failure point.

It is to be understood that various alterations, modifications and/oradditions may be introduced into the construction and arrangement of theparts previously described without departing from the spirit or ambit ofthis invention.

1. A portable pump comprising: a reciprocating air compressorarrangement, the air compressor arrangement comprising: a crank thatdrives a connecting rod and a piston within a cylinder, the connectingrod having a first end and a second end, the first end of the connectingrod connected to the crank and the second end of the connecting rodconnected to the piston, with the crank provided to actuate the pistonin a reciprocating motion within and relative to the cylinder so as tocompress air within the cylinder, the reciprocating air compressorarrangement having a one-way flapper inlet valve allowing air to enterthe cylinder, and a one-way outlet valve allowing compressed air to exitthe cylinder, wherein the inlet valve is biased to a partially openposition; an electric motor having a drive shaft mounted to the crank,with the drive shaft rotatable about a drive shaft axis, and with thedrive shaft axis at least substantially coaxially aligned with an axisof rotation of the crank; a control unit in electrical communicationwith the electric motor to control operation of the pump; a power supplyin electrical communication with the control unit to supply power to thecontrol unit and electric motor; the electric motor, the reciprocatingair compressor arrangement, the control unit and the power supply eachcontained within a common housing; and an outlet fluidly connected tothe outlet valve of the reciprocating air compressor arrangement forfluidly engaging with an object to be pumped.
 2. A portable pumpaccording to claim 1, wherein the cylinder comprises a cylinder head,and the outlet valve comprises an outlet port, with the outlet portextending through the cylinder head to allow for a flow of compressedair to exit the cylinder.
 3. A portable pump according to claim 1,wherein the inlet valve comprises an inlet port, with the inlet portextending through the cylinder head to allow for a flow of air to enterthe cylinder.
 4. A portable pump according to claim 1, wherein thepiston comprises a piston head, and the inlet valve comprises an inletport, with the inlet port extending through the piston head to allow fora flow of air to enter the cylinder.
 5. A portable pump according toclaim 1, wherein during operation of the portable pump, the inlet valveis movable between the partially open position, a fully open positionand a closed position.
 6. A portable pump according to claim 5, whereinthe portable pump is switchable between ON and OFF modes, and the inletvalve remains in the partially open position when the portable pump isin the OFF mode.
 7. A portable pump according to claim 1, wherein thepower supply is a rechargeable battery having a C rating of at leastapproximately 20, and capable of providing a maximum current of at least4 Amps.
 8. A portable pump according to claim 1, wherein the electricmotor is a brushless DC motor having a motor diameter of betweenapproximately 20 and 30 mm, and preferably approximately 23 mm.
 9. Aportable pump according to claim 1, wherein the pump has a total weightof less than 100 grams, and can pump up at least one bicycle road orcommuter bike tyre to approximately 80 psi on a single charge.
 10. Aportable pump according to claim 1, wherein the housing has a length ofbetween approximately 45 and 65 mm, a height of less than approximately50 mm, and a width (or thickness) of approximately 25 mm.
 11. A portablepump according to claim 1, wherein the outlet is provided on or mountedto the housing.
 12. A portable pump according to claim 11, wherein theoutlet comprises a collar extending outwardly from the housing, thecollar comprising a valve receiving bore for receiving a valve of theobject to be pumped.
 13. A portable pump according to claim 1, whereinthe outlet valve is a flapper valve or a check valve.
 14. Areciprocating air compressor arrangement comprising: a crank that drivesa connecting rod and a piston within a cylinder, the connecting rodhaving a first end and a second end, the first end of the connecting rodconnected to the crank and the second end of the connecting rodconnected to the piston, with the crank provided to actuate the pistonin a reciprocating motion within and relative to the cylinder so as tocompress air within the cylinder, the reciprocating air compressorarrangement having a one-way flapper inlet valve allowing air to enterthe cylinder, and a one-way outlet valve allowing compressed air to exitthe cylinder; wherein the inlet valve is biased to a partially openposition.
 15. A reciprocating air compressor arrangement according toclaim 14, wherein the cylinder comprises a cylinder head, and the outletvalve comprises an outlet port, with the outlet port extending throughthe cylinder head to allow for a flow of compressed air to exit thecylinder.
 16. A reciprocating air compressor arrangement according toclaim 14, wherein the inlet valve comprises an inlet port, with theinlet port extending through the cylinder head to allow for a flow ofair to enter the cylinder.
 17. A reciprocating air compressorarrangement according to claim 14, wherein the piston comprises a pistonhead, and the inlet valve comprises an inlet port, with the inlet portextending through the piston head to allow for a flow of air to enterthe cylinder.
 18. A reciprocating air compressor arrangement accordingto claim 14 wherein, during operation of the air compressor arrangement,the inlet valve is movable between the partially open position, a fullyopen position and a closed position.
 19. A reciprocating air compressorarrangement according to claim 18, wherein the air compressorarrangement is switchable between ON and OFF modes, and the inlet valveremains in the partially open position when the air compressorarrangement is in the OFF mode.
 20. A reciprocating air compressorarrangement according to claim 14, wherein the outlet valve is a flappervalve or a check valve.